plotter: Change default width for HTML plots
plotter: Change default width for HTML plots

HTML plots fit better with the width value of 900 expecially on
IPython > 3

Change-Id: Ife9f9ae82336e8a4eb224eb33708996a408953ed
Signed-off-by: Kapileshwar Singh <d373e2b6407ea84be359ce4a11e8631121819e79@arm.com>

derkling/trappy,derkling/trappy,JaviMerino/trappy,ARM-software/trappy,bjackman/trappy,joelagnel/trappy,sinkap/trappy,ARM-software/trappy,ARM-software/trappy,sinkap/trappy,JaviMerino/trappy,joelagnel/trappy,joelagnel/trappy,bjackman/trappy,bjackman/trappy,bjackman/trappy,joelagnel/trappy,sinkap/trappy,JaviMerino/trappy,derkling/trappy,ARM-software/trappy,sinkap/trappy